Orthodontic surgeons and Otorhinolaryngologists are known to analyze the patient's upper airway-volume. There are many clinical applications for the evaluation of the upper airway volumetric analysis, such as diagnosis of obstructive sleep apnea, evaluation of sinus anatomy, and dento-maxillofacial morphology in cephalometric analysis etc. Obstruction of upper airway leads to obstructive sleep apnea (OSA). Segmentation of upper airway volume helps to identify the region of obstruction and volumetric measurements of the segmented data for further analysis and surgery.
Conventionally, X-ray radiographs were used for the evaluation of airway anatomy. The airway analysis is performed based on the various linear and angular measurements made on the lateral X-ray films. This analysis is performed without calculating true volume, which is not appropriate for the clinical diagnosis and therefore treatment planning likely not to be significantly effective due to probable error in volume analysis. The evolution of CT/CBCT has made possible to visualize the true volume of airway. Eventually, segmentation of the desired volume becomes possible manually.
There are a host of manual/semi-automatic segmentation techniques available such as region growing, fixed thresholding, interactive thresholding etc. These techniques require a high level of human interventions, time and efforts, and are also dependent on human perception and experience. It makes the segmentation tedious for the observer and raises a need for automation.